Center punch



May 6, 1952 v P. s. H. FLEMMING CENTER PUNCH Filed Aug. 5, 1949" FIG. 2-.

FIG. I.

IIIIIIIII Patented May 6, 1952 CENTER PUNCH Paul Svend Hakon Flemming, Copenhagen, Denmark Application August 5, 1949, Serial No. 108,730 In Denmark February 22, 1949 1 Claim. 1 This invention relates to center punches for marking oil workpieces prior to drilling bolt holes or the like, the punch being positioned relative to the workpiece by means of a jig or fixture provided with holes presenting the outlines of the holes to be marked off and drilled.

More specifically, the invention aims to provide a self-centering punch of a simple and compact construction which is easy to handle and effective in operation.

Furthermore, it is the object of the invention to provide a center punch of the kind referred to having a simple and efficient means for insuring a position of the axis of the punch perpendicular to the face of the workpiece to be marked oil.

Another object is to generally improve the center punches of the type in question.

Referring now to the drawing:

Fig. l is an axial sectional view of a center punch in accordance with this invention, and

Fig. 2 is a side elevation thereof.

In the drawing, 4a is a tubular guide having a conical end 612 so as to present the shape of a truncated cone at its lower end. The axial bore of the guide is restricted at the conical end of the same so as to provide an interior shoulder 19. A cylindrical punch rod la having a conically pointed end 3 adapted to project from the conical end 6a of the guide 4a is mounted for axially sliding movement in the guide, the pointed end of the punch rod la being guided in the restricted portion of the bore of the guide, and the opposite end, which is adapted to project from the guide, being guided in a cap or nut [2a screwed on the upper or rear end of the guide. The punch rod la is formed with a flange 8a or like laterally projecting member, and a helical spring Illa is interposed between said flange and the shoulder I9 to hold the punch rod la in a retracted position, as indicated in Fig. 1, the cap [2a constituting an abutment cooperating with the flange 8a to limit retraction of the punch rod. The construction so far described is known.

The guide d is slidable longitudinally within a holder Ha abutting with its upper end against the cap or nut [2a. The inner wall of the holder lid is formed with a shoulder I3, whilst the circumference of the guide 4a is formed with another shoulder i 4, and between these shoulders is interposed a coil spring which acts to hold the member Ha resiliently against the nut II. The lower end of the holder I la is formed with an end face Ila at right angles to the axis of the punch rod la.

When using the center punch described, a suitable jig (not shown) is placed on the workpiece 2 to be marked off, and the-conical end (in of the punch is inserted in the hole of the jig or fixture, the operator gripping the preferably knurled circumference of the holder Ila and urging the holder downwards against the action of the spring I5 to cause the face Ila to engage the jig so as to insure that the axis of the punch rod la is perpendicular to the face to be marked off. The

upwardly projecting end of the punch rod is now struck with a hammer to cause the pointed end 3 to mark oil the center of the hole to be drilled.

Iclaim:

A center punch comprising in combination a tubular guide, an interior shoulder in said guide, a punch having a pointed end and mounted for longitudinal sliding movement in said guide, means associated with said punch and projecting laterally therefrom within said guide, spring means interposed between said interior shoulder and said laterally projecting means for holding said punch with the pointed end thereof in a retracted position in the mouth of said guide and with the opposite end of said punch projecting from the opposite end of said guide, a tubular holder mounted for axially sliding movement on said guide, said holder being at one end provided with an interior shoulder engaging the circumference of said guide, and said guide being provided with a circumferential shoulder engaging the inner wall of said holder, spring means interposed between said lastna-med interior shoulder and said circumferential shoulder and adapted to retract said holder from the end of said guide surrounding the pointed end of said punch, and a nut screwed onto the end of said guide remote from the pointed end of said punch and formed with means constituting abutments for limiting retraction of said holderand said punch, respectively.

PAUL SVEND HAKON FLEMMING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 93,937 Wilcox Aug. 17, 1869 184,562 Waste Nov. 21, 1876 1,029,386 Mays June 11, 1912 1,225,265 Miller May 8, 1917 2,233,458 Fisk July 17, 1917 FOREIGN PATENTS Number Country Date 52,227 Austria Feb. 26, 1912 142,838 Germany July 23, 1903 

